<html><!-- Created using the cpp_pretty_printer from the dlib C++ library.  See http://dlib.net for updates. --><head><title>dlib C++ Library - disjoint_subsets.h</title></head><body bgcolor='white'><pre>
<font color='#009900'>// Copyright (C) 2011  Davis E. King (davis@dlib.net)
</font><font color='#009900'>// License: Boost Software License   See LICENSE.txt for the full license.
</font><font color='#0000FF'>#ifndef</font> DLIB_DISJOINT_SUBsETS_Hh_
<font color='#0000FF'>#define</font> DLIB_DISJOINT_SUBsETS_Hh_

<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='disjoint_subsets_abstract.h.html'>disjoint_subsets_abstract.h</a>"
<font color='#0000FF'>#include</font> <font color='#5555FF'>&lt;</font>vector<font color='#5555FF'>&gt;</font>
<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='../algs.h.html'>../algs.h</a>"

<font color='#0000FF'>namespace</font> dlib
<b>{</b>

<font color='#009900'>// ----------------------------------------------------------------------------------------
</font>
    <font color='#0000FF'>class</font> <b><a name='disjoint_subsets'></a>disjoint_subsets</b>
    <b>{</b>
    <font color='#0000FF'>public</font>:

        <font color='#0000FF'><u>void</u></font> <b><a name='clear'></a>clear</b> <font face='Lucida Console'>(</font>
        <font face='Lucida Console'>)</font>
        <b>{</b>
            items.<font color='#BB00BB'>clear</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font>;
        <b>}</b>

        <font color='#0000FF'><u>void</u></font> <b><a name='set_size'></a>set_size</b> <font face='Lucida Console'>(</font>
            <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> new_size
        <font face='Lucida Console'>)</font>
        <b>{</b>
            items.<font color='#BB00BB'>resize</font><font face='Lucida Console'>(</font>new_size<font face='Lucida Console'>)</font>;
            <font color='#0000FF'>for</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> i <font color='#5555FF'>=</font> <font color='#979000'>0</font>; i <font color='#5555FF'>&lt;</font> items.<font color='#BB00BB'>size</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font>; <font color='#5555FF'>+</font><font color='#5555FF'>+</font>i<font face='Lucida Console'>)</font>
            <b>{</b>
                items[i].parent <font color='#5555FF'>=</font> i;
                items[i].rank <font color='#5555FF'>=</font> <font color='#979000'>0</font>;
            <b>}</b>
        <b>}</b>

        <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> <b><a name='size'></a>size</b> <font face='Lucida Console'>(</font>
        <font face='Lucida Console'>)</font> <font color='#0000FF'>const</font>
        <b>{</b>
            <font color='#0000FF'>return</font> items.<font color='#BB00BB'>size</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font>;
        <b>}</b>

        <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> <b><a name='find_set'></a>find_set</b> <font face='Lucida Console'>(</font>
            <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> item 
        <font face='Lucida Console'>)</font> <font color='#0000FF'>const</font>
        <b>{</b>
            <font color='#009900'>// make sure requires clause is not broken
</font>            <font color='#BB00BB'>DLIB_ASSERT</font><font face='Lucida Console'>(</font>item <font color='#5555FF'>&lt;</font> <font color='#BB00BB'>size</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font>, 
                "<font color='#CC0000'>\t unsigned long disjoint_subsets::find_set()</font>"
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t item must be less than size()</font>"
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t item: </font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> item 
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t size(): </font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> <font color='#BB00BB'>size</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> 
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t this: </font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> <font color='#0000FF'>this</font>
                <font face='Lucida Console'>)</font>;

            <font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>items[item].parent <font color='#5555FF'>=</font><font color='#5555FF'>=</font> item<font face='Lucida Console'>)</font>
            <b>{</b>
                <font color='#0000FF'>return</font> item;
            <b>}</b>
            <font color='#0000FF'>else</font>
            <b>{</b>
                <font color='#009900'>// find root of item
</font>                <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> x <font color='#5555FF'>=</font> item;
                <font color='#0000FF'>do</font>
                <b>{</b>
                    x <font color='#5555FF'>=</font> items[x].parent;
                <b>}</b> <font color='#0000FF'>while</font> <font face='Lucida Console'>(</font>items[x].parent <font color='#5555FF'>!</font><font color='#5555FF'>=</font> x<font face='Lucida Console'>)</font>;

                <font color='#009900'>// do path compression
</font>                <font color='#0000FF'>const</font> <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> root <font color='#5555FF'>=</font> x;
                x <font color='#5555FF'>=</font> item;
                <font color='#0000FF'>while</font> <font face='Lucida Console'>(</font>items[x].parent <font color='#5555FF'>!</font><font color='#5555FF'>=</font> x<font face='Lucida Console'>)</font>
                <b>{</b>
                    <font color='#0000FF'>const</font> <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> prev <font color='#5555FF'>=</font> x;
                    x <font color='#5555FF'>=</font> items[x].parent;
                    items[prev].parent <font color='#5555FF'>=</font> root;
                <b>}</b>

                <font color='#0000FF'>return</font> root;
            <b>}</b>
        <b>}</b>

        <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> <b><a name='merge_sets'></a>merge_sets</b> <font face='Lucida Console'>(</font>
            <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> a,
            <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> b
        <font face='Lucida Console'>)</font>
        <b>{</b>
            <font color='#009900'>// make sure requires clause is not broken
</font>            <font color='#BB00BB'>DLIB_ASSERT</font><font face='Lucida Console'>(</font>a <font color='#5555FF'>!</font><font color='#5555FF'>=</font> b <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font>
                        a <font color='#5555FF'>&lt;</font> <font color='#BB00BB'>size</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font>
                        b <font color='#5555FF'>&lt;</font> <font color='#BB00BB'>size</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font> 
                        <font color='#BB00BB'>find_set</font><font face='Lucida Console'>(</font>a<font face='Lucida Console'>)</font> <font color='#5555FF'>=</font><font color='#5555FF'>=</font> a <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font>
                        <font color='#BB00BB'>find_set</font><font face='Lucida Console'>(</font>b<font face='Lucida Console'>)</font> <font color='#5555FF'>=</font><font color='#5555FF'>=</font> b,
                "<font color='#CC0000'>\t unsigned long disjoint_subsets::merge_sets(a,b)</font>"
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t invalid arguments were given to this function</font>"
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t a: </font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> a 
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t b: </font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> b 
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t size(): </font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> <font color='#BB00BB'>size</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> 
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t find_set(a): </font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> <font color='#BB00BB'>find_set</font><font face='Lucida Console'>(</font>a<font face='Lucida Console'>)</font> 
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t find_set(b): </font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> <font color='#BB00BB'>find_set</font><font face='Lucida Console'>(</font>b<font face='Lucida Console'>)</font> 
                <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> "<font color='#CC0000'>\n\t this: </font>" <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> <font color='#0000FF'>this</font>
                <font face='Lucida Console'>)</font>;

            <font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>items[a].rank <font color='#5555FF'>&gt;</font> items[b].rank<font face='Lucida Console'>)</font>
            <b>{</b>
                items[b].parent <font color='#5555FF'>=</font> a;
                <font color='#0000FF'>return</font> a;
            <b>}</b>
            <font color='#0000FF'>else</font>
            <b>{</b>
                items[a].parent <font color='#5555FF'>=</font> b;
                <font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>items[a].rank <font color='#5555FF'>=</font><font color='#5555FF'>=</font> items[b].rank<font face='Lucida Console'>)</font>
                <b>{</b>
                    items[b].rank <font color='#5555FF'>=</font> items[b].rank <font color='#5555FF'>+</font> <font color='#979000'>1</font>;
                <b>}</b>
                <font color='#0000FF'>return</font> b;
            <b>}</b>
        <b>}</b>

    <font color='#0000FF'>private</font>:

        <font color='#009900'>/*
            See the book Introduction to Algorithms by Cormen, Leiserson, Rivest and Stein
            for a discussion of how this algorithm works.
        */</font>

        <font color='#0000FF'>struct</font> <b><a name='data'></a>data</b>
        <b>{</b>
            <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> rank;
            <font color='#0000FF'><u>unsigned</u></font> <font color='#0000FF'><u>long</u></font> parent;
        <b>}</b>;

        <font color='#0000FF'>mutable</font> std::vector<font color='#5555FF'>&lt;</font>data<font color='#5555FF'>&gt;</font> items;

    <b>}</b>;

<font color='#009900'>// ----------------------------------------------------------------------------------------
</font>
<b>}</b>

<font color='#0000FF'>#endif</font> <font color='#009900'>// DLIB_DISJOINT_SUBsETS_Hh_
</font>

</pre></body></html>